The present invention relates to an apparatus for delivering filtered, ionized air into spaces, such as the clean room of a manufacturing plant for electronic equipment.
It is known that certain industrial operations benefit from being performed in substantially dust-free atmosphere. To that end, rooms designated as "clean rooms" are provided, which are sealed against the entry of air, except air which is intentionally delivered into the room, this air being filtered. In the installation of these clean rooms, the air is preferably filtered through a type of filter known as a HEPA filter, which is highly effective in removing all but the smallest particles of dust.
It has been recognized, however, that even these HEPA filters did not provide a sufficient cleansing of the air, and that, in fact, some very small dust particles passed through the HEPA filter and entered the room, to the detriment of the manufacturing operations proceeding therein. For example, dust particles which were statically charged could contact work products in process, and render them useless. Such work products include microcircuits.
To overcome this problem, it has been known to provide ionizing units to ionize the air, and the particles, so as to render them statically neutral. In some installations, the HEPTA filters were produced as filter units, having an entry port connected to an air duct, and having a discharge face. These filter units were placed on a support grid, suspended from the ceiling, the support grid being made up, in known fashion, of T-rails. Ionizing units, in the form of grids, were simply suspended below the discharge face of the filter unit, as by S-hooks.
The foregoing systems was unsatisfactory for several reasons. First, since the ionizing unit was at a location below the discharge face of the filter unit, it was possible for some of the filtered air, containing statically charged dust particles, to pass through the space between the discharge face of the filter unit and the ionizing unit, thereby passing outwardly and bypassing the ionizing unit. Thus, there was permitted the discharge of statically charged particles into the clean room. Further, the appearance was less attractive than desirable, there being provided a built-on or jury-rig appearance.